Method and apparatus for broadband data conversion

ABSTRACT

A receiver may receive a signal and process each of a plurality of sub-bands of the received signal via a respective one of a plurality of first-type receive chains. The receiver may utilize a signal output by a first one of the plurality of the first-type receive chains to remove undesired signals from a signal output by a second one of the plurality of the first-type receive chains. The undesired signals may comprise aliases and/or harmonics of one or more signals that fall within a sub-band of the first one of the plurality of the first-type receive chains. The receiver may downconvert, filter, and digitize each of the plurality of sub-bands via a corresponding one of the plurality of the first type receive chains. The received signal may encompass the cable television band, and each of the plurality of sub-bands may comprise a plurality of cable television channels.

CLAIM OF PRIORITY

This patent application makes reference to, claims priority to andclaims benefit from U.S. Provisional Patent Application Ser. No.61/427,088 filed on Dec. 23, 2010.

The above-incorporated application is hereby incorporated herein byreference in its entirety.

INCORPORATION BY REFERENCE

This patent application also makes reference to U.S. patent applicationSer. No. 12/432,666 filed on Apr. 29, 2009.

The above-incorporated application is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to signal processing. Morespecifically, certain embodiments of the invention relate to a methodand apparatus for broadband data conversion.

BACKGROUND OF THE INVENTION

Conventional methods and systems for data conversion are too large,power intensive, and inflexible. Further limitations and disadvantagesof conventional and traditional approaches will become apparent to oneof skill in the art, through comparison of such systems with someaspects of the present invention as set forth in the remainder of thepresent application with reference to the drawings.

BRIEF SUMMARY OF THE INVENTION

A system and/or method is provided for broadband data conversion,substantially as illustrated by and/or described in connection with atleast one of the figures, as set forth more completely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a portion of the frequency spectrum in a cabletelevision system.

FIG. 2 is a diagram illustrating broadband data conversion utilizing asingle receive chain.

FIG. 3 is a diagram illustrating segmenting of the cable televisionspectrum for data conversion utilizing a plurality of analog-to-digitalconverter.

FIG. 4 is a diagram illustrating broadband data conversion utilizing aplurality of receive chains.

FIG. 5A-5G depict exemplary signals of the receiver shown in FIG. 4.

FIG. 6A-6B depict power management in a receiver comprising a pluralityof sub-band receive chains.

DETAILED DESCRIPTION OF THE INVENTION

As utilized herein the terms “circuits” and “circuitry” refer tophysical electronic components (i.e. hardware) and any software and/orfirmware (“code”) which may configure the hardware, be executed by thehardware, and or otherwise be associated with the hardware. As utilizedherein, “and/or” means any one or more of the items in the list joinedby “and/or”. As an example, “x and/or y” means any element of thethree-element set {(x), (y), (x, y)}. As another example, “x, y, and/orz” means any element of the seven-element set {(x), (y), (z), (x, y),(x, z), (y, z), (x, y, z)}. As utilized herein, the terms “block” and“module” refer to functions than can be implemented in hardware,software, firmware, or any combination of one or more thereof. Asutilized herein, the term “exemplary” means serving as a non-limitingexample, instance, or illustration. As utilized herein, the term “e.g.,”introduces a list of one or more non-limiting examples, instances, orillustrations.

FIG. 1 is a diagram of a portion of the frequency spectrum in a cabletelevision system. The cable band 102 spans from 54 MHz to 1005 Mhz. Thedepicted (Multimedia over Coax Alliance) MoCA band (“Band D” of the MoCAspecification) spans from approximately 1150 MHz to 1500 MHz. The cableband comprises a plurality of channels 106, which may be, for example, 6or 8 MHz wide. In the embodiment depicted, there are 158 channels ofwhich exemplary channels 106 ₁, 106 ₂, 106 ₃, 106 ₈₀, and 106 ₁₅₈ areshown.

FIG. 2 is a diagram illustrating broadband data conversion utilizing asingle receive chain. The portion 100 of the receiver comprises variablegain amplifier (VGA) 120, an anti-aliasing filter (AAF) 124, ananalog-to-digital converter (ADC) 126, a digital signal processor (DSP)108, and a high-speed data interface 110.

In operation, the variable gain amplifier (VGA) 120 may amplify areceived cable television signal across the entire band 102. The AAF 124may filter this signal to select the cable band 102 and remove otherbands such as the MoCA band 104. The ADC 126 may then digitize theentire band 102. The DSP 108 then processes the digitized band 102 andconveys digital signals to the interface 110 for output to a videoprocessor or a gateway system on chip (SoC). Because of the widebandwidth and sharp roll-off needed for the AAF 124, it is typically alarge and expensive component that is realized on a separate chip.Similarly, because of the large bandwidth of the band 102, the ADC 126needs to have very high performance, making it another expensivecomponent. Accordingly, aspects of the invention enable reducing theperformance requirements of an anti-aliasing filter and ADC such that acable television receiver may utilize smaller and/or cheaper components.

FIG. 3 is a diagram illustrating segmenting of the cable televisionspectrum for data conversion utilizing a plurality of analog-to-digitalconverter. Referring to FIG. 3, the cable spectrum is segmented intosub-bands 302 ₁-302 _(B). Although four sub-bands are utilized forillustration, the cable spectrum 102 may be segmented into any integernumber, B, of sub-bands without deviating from the scope of the presentinvention. The bandwidth of the sub-bands may be chosen based on, forexample, size and/or cost constraints of the ADCs and/or AAFs utilizedto process the sub-bands. The sub-bands 302 ₁-302 ₄ may benon-overlapping and/or may be substantially non-overlapping with arelatively small amount of overlap (e.g., a few MHz for a ˜250 MHz widesub-band) to provide some guard band at the edges of the sub-bands.

FIG. 4 is a diagram illustrating broadband data conversion utilizing aplurality of receive chains. The receiver 400 of FIG. 4 comprises avariable gain amplifier 402, a local oscillator (LO) generation module420, a digital signal processing module (DSP) 428, a high-speed datainterface module 110, and a plurality of receive chains 404 ₁-404 _(B).Each of the receive chains 404 ₁-404 _(B) may comprise an amplifier 410_(b), a mixer 412 _(b), an AAF 414 _(b), and an ADC 416 _(b), where b isan integer between 1 and B. In an exemplary embodiment, the receiver 400may be a system on chip integrated on a single die, or may comprise aplurality of dies.

In an exemplary embodiment, each of the receive chains 404 ₁-404 _(B)operates over a narrow and/or substantially-fixed frequency band.Accordingly, each of the receive chains 404 ₁-404 _(B) may be optimizedfor its respective band(s) rather than needing to be designed to coverthe entire cable spectrum. As a result, each of the receive chains 404₁-404 _(B) may be smaller, less expensive, and/or lower power than thereceive chain 100 described with respect to FIG. 2.

In an exemplary embodiment, one or more of the receive chains 404 ₁-404_(B) may be configurable to operate over a one or more sub-bands thatoverlap with one or more sub-bands which are processed by other ones ofthe receive chains. For example, one of the receive chains 404 ₁-404_(B) may be operable to process the entire cable band 102 while each ofthe other receive chains 404 ₁-404 _(B) processes a respective one ofthe sub-bands.

The variable gain amplifier (VGA) 402 may comprise circuitry operable toamplify a received cable television signal across the entire band 102.The gain of the VGA 402 may be controlled via one or more controlsignals (not shown) and may be controlled, for example, via an automaticgain control loop.

The LO generator 420 may comprise circuitry for generating localoscillator signals LO₁-LO_(B). In an exemplary embodiment, each of thesignals LO₁-LO_(B) may be a pair of signals in phase-quadrature. Invarious embodiments, a phase and/or frequency of one or more LO₁-LO_(B)may be fixed, programmable, or dynamically controlled via, for example,a feedback loop.

Each amplifier 410 _(b) may comprise circuitry operable to amplify thesub-band 302 _(b) of the amplified cable signal output by the VGA 402.In an exemplary embodiment, each amplifier 410 _(b) may providefrequency selectivity (e.g., low-pass, bandpass, or high-pass filtering)such that the band 302 _(b) is amplified by the amplifier 410 _(b) whileother sub-bands are not amplified or are even attenuated by theamplifier 410 _(b).

Each mixer 412 _(b) may comprise circuitry operable to down-convert thesub-band 302 _(b) to an intermediate frequency or to baseband by mixingthe signal output from amplifier 410 _(b) with the signal LO_(b) outputby the LO generator 420. Each mixer 412 _(b) may, for example, be asdescribed in the above-incorporated U.S. patent application Ser. No.12/432,666.

Each anti-aliasing filter 414 _(b) may comprise circuitry operable tolow-pass and/or band-pass filter the output of the mixer 412 _(b) toreducing aliasing in the ADC 416 _(b). In an exemplary embodiment, thecenter frequency and/or bandwidth of the AAF 414 _(b) may be fixed,programmable, and/or dynamically controlled during operation of thereceive chain 404 _(b) via, for example, a feedback loop. In anexemplary embodiment, the bandwidth of the filter 414 _(b) may becontrolled based on the bandwidth of the sub-band 302 _(b).

Each analog-to-digital converter (ADC) 416 b may comprise circuitryoperable to convert the filtered analog signal output by filter 414 _(b)into a digital representation. In an exemplary embodiment, the samplerate, resolution, and/or dynamic range of the ADC 416 _(b) may be fixed,programmable, and/or dynamically controlled during operation of thereceive chain 404 _(b) via, for example, a feedback loop. In anexemplary embodiment, the sample rate of the ADC 416 _(b) may becontrolled based on the bandwidth of the sub-band 302 _(b).

The digital signal processor (DSP) 428 may comprise circuitry operableto process the digital signals received from the ADCs 416 ₁-416 _(B) torecover information contained in the signals. For example, the DSP 428may perform calibration, filtering, demodulation, error correction,and/or other functions. In an exemplary embodiment, the DSP 428 may beoperable to cancel out signal aliases and and/or inter-modulationproducts as, for example, described below with respect to FIGS. 5A and5B.

The DSP 428 may also be operable to generate control signals forconfiguring the receive chains 404 ₁-404 _(B) and/or the LO generator420. For example, the DSP 428 may control the frequencies of the signalsLO₁-LO₄, the gain of the VGA 402 and amplifiers 410 ₁-410 ₄, the cutoffand/or center frequencies of the filter 414 ₁-414 ₄, and/or theresolution, dynamic range, and/or sampling frequency of the ADC 416₁-416 ₄. In an exemplary embodiment, as described below with respect toFIGS. 6A-6B, the DSP 428 may be operable to enable and disablecomponents (e.g., connect and disconnect supply power and/or toggle anenable input of the components) of the receive chains 404 ₁-404 ₄ tomanage power consumption of the receiver 400.

The high-speed data interface 110 may comprise circuitry for receivingdata from the DSP 428 and processing the data for communication over adata bus. The high-speed data interface 110 may support variousprotocols such as one or more of PCMCIA, Ethernet, MoCA, USB, IEEE 1394,and/or any other suitable protocol.

In operation, the entire cable band 102 may be amplified by the variablegain amplifier 402 and the output of the variable gain amplifier 402 maybe conveyed to each of the amplifiers 410 ₁-410 _(B). Each amplifier 410_(b) may then amplify the sub-band 302 _(b). Each mixer may thendown-convert the output of the amplifier 410 _(b) to an intermediatefrequency or to baseband by mixing the output of amplifier 410 _(b) withsignal LO_(b). The down-converted signal may be processed via filter 414_(b), and the downconverted and filtered signal may be digitized by theADC 416 _(b). The DSP 428 may then process the signals from each of theADCs 416 ₁-416 _(B) to recover information carried in one or more of thecable television channels 106. The recovered information may then beconveyed to the high-speed interface 100 which may convey the recoveredinformation to, for example another circuit in the same device (e.g.,where the receiver 400 resides in a set-top box or gateway) and/or toanother device (e.g., to a client device such as a computer or atelevision).

The processing of the signals output by the DSP 428 may comprisedetecting signals present in each of the sub-bands 302 ₁-302 _(B)calculating harmonics and/or aliases of the detected signals and/or LOsignals LO₁-LO₄ that fall within one or more of the sub-bands 302 ₁-302_(B), and cancelling those harmonics and/or aliases. This calculationmay be performed utilizing knowledge of the frequencies of the signalsLO₁-LO₄, knowledge of the frequency response of the filters 414 ₁-414_(B), and knowledge of sampling frequencies of the ADCs 416 ₁-416 ₁₃.Exemplary processing of signals by the DSP 428, via an embodiment of thereceiver 400 in which B=4, is described with respect to FIGS. 5A-5G.

Referring to FIG. 5A, an exemplary spectrum of signals received by thereceiver 400 is shown. The spectrum comprises signal 502 located insub-band 302 ₂, signal 504 located in sub-band 302 ₃, and signal 506located in sub-band 302 ₄. Each of the signals 502, 504, and 506 may be,for example, a television channel. Also shown are the local oscillatorsignals LO₁-LO₄ and the third harmonic of LO₁, which falls in sub-band302 ₄. For purposes of illustration, the signal 502 is the signaldesired to be output by the receiver 400.

FIG. 5B shows the output of Mixer 412 ₂ when the signal of FIG. 5A isinput to it. That is, FIG. 5B shows the downconverted version of thespectrum in FIG. 5A (assuming that there is insignificant leakage ofsignals LO₂-LO₄ into the receive chain 404 ₂). In the exemplaryembodiment shown in FIG. 5B, the receiver 400 is a zero-IF receiver andthus the spectrum shown in FIG. 5B is centered around DC (0 Hz).

FIG. 5C shows the filtering of the output of the mixer 412 ₂ by thefilter 414 ₂. The dashed line 520 represents the frequency response ofthe filter 414 ₂. Compared to the frequency response of the filter 124in FIG. 2, the filter 414 ₂ may have a slower roll-off that can beachieved via smaller and/or less-expensive circuitry. The slow roll-offof filter 414 ₂, however, results in the out-of-sub-band signal 504still having significant power at the output of the filter 414 ₂.Consequently, when the output of the filter 414 ₂ is digitized utilizingsampling frequency fs, as shown in FIG. 5D, the signal 504 may alias toa frequency very near the desired signal 502. Accordingly, the signal504′ may make it difficult to recover the desired signal 502.

As shown in FIGS. 5E and 5F, however, the signal 504 falls within thesub-band operated on by the receive chain 404 ₃. Accordingly, the DSP428 may detect the signal 504 in the output of the ADC 416 ₃, calculatethe frequency of alias 504′ based on its knowledge of the samplingfrequency fs, and then cancel out the alias 504′. A similar approach maybe taken to cancel out the aliases 506′ and 502′ shown in FIG. 5Gutilizing the signals received from receive chains 404 ₄ and 404 ₂,respectively, and knowledge of the sampling frequency fs. Moreover, thiscancellation approach may be applied to aliases and harmonics appearingin each of the receive chains 404 ₁-404 ₄. That is the DSP 428 mayutilize the signal received from each one of the receive chains 404₁-404 ₄, to cancel out undesired signals occurring in the signalsreceived from other ones of the receive chains 404 ₁-404 ₄.

FIG. 6A-6B depict power management in a receiver comprising a pluralityof sub-band receive chains. Shown in FIG. 6A, the receiver 400 mayreceive a signal in which there is a desired channel in each ofsub-bands 302 ₁-302 ₄. Each of the desired channels 602, 604, 606, and608 may, for example, be a television channel selected for consumptionby a downstream device (e.g., a television or digital video recorderwhich receives content from the receiver 400). Accordingly, to enablereception of each of the desired channels 602, 604, 606, and 608, theDSP 428 may configure the receiver 400 such that each of the receivechains 404 ₁-404 ₄ is powered up (as indicated by the components beingbolded). In FIG. 6B, on the other hand, the desired channels 602, 604,606, and 608 reside in sub-bands 302 ₃ and 302 ₄. Accordingly, receivechains 404 ₃ and 404 ₄ are powered up to process bands 302 ₃ and 302 ₄whereas receive chains 404 ₁ and 404 ₂ are powered down to reduce powerconsumption.

In an exemplary embodiment, a receiver (e.g., receiver 400) may receivea signal (e.g., a cable television signal), and process each of aplurality of sub-bands of the received signal (e.g., each sub-band 302_(b)) via a respective one of a plurality of first-type receive chainsof the receiver (e.g., receive chain 404 _(b) configured to processsub-band 302 _(b)). The receiver may utilize a signal output by a firstone of the plurality of first-type receive chains (e.g., signal outputby receive chain 404 ₂) to remove undesired signals from a signal outputby a second one of the plurality of first-type receive chains (e.g.,signal output by receive chain 404 ₃). The undesired signals maycomprise aliases and/or harmonics of one or more signals that fallwithin a sub-band of the first one of the plurality of first-typereceive chains.

The receiver may downconvert, filter, and digitize each of the pluralityof sub-bands (e.g., bands 302 ₁-302 ₄) via a corresponding one of theplurality of receive chains (e.g., receive chains 404 ₁-404 ₄). Each ofthe plurality of first-type of receive chains may downconvert arespective one of the plurality of sub-bands utilizing a respective oneof a plurality of fixed-frequency local oscillator signals (e.g.,signals LO₁-LO₄). A frequency of each of the plurality offixed-frequency local oscillator signals may be different than afrequency of each other one of the plurality of fixed-frequency localoscillator signals. The receiver may control whether one or more of theplurality of first-type receive chains is enabled or disabled based onwhether a channel to be output by the receiver (e.g., one of thechannels 602-608) is located in a sub-band of the received signal thatis processed by the one or more of the first-type receive chains.

The received signal may encompass the cable television band, and each ofthe plurality of sub-bands may comprise a plurality of cable televisionchannels. The receiver may concurrently process all sub-bands of thereceived signal via at least one second-type receive chain of thereceiver (e.g., a receive chain 404 _(b) configured to process entirecable band). Each one of the plurality of sub-bands may be substantiallynon-overlapping with each other one of the plurality of sub-bands.

Other embodiments of the invention may provide a non-transitory computerreadable medium and/or storage medium, and/or a non-transitory machinereadable medium and/or storage medium, having stored thereon, a machinecode and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for Method andapparatus for broadband data conversion.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputing system, or in a distributed fashion where different elementsare spread across several interconnected computing systems. Any kind ofcomputing system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computing system with a program orother code that, when being loaded and executed, controls the computingsystem such that it carries out the methods described herein. Anothertypical implementation may comprise an application specific integratedcircuit or chip.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A system comprising: one or more circuits of areceiver, said one or more circuits comprising a plurality of first-typereceive chains, each of said plurality of first-type receive chainsbeing operable to process a respective one of a plurality of sub-bandsof a received signal; and a digital signal processing module operable toutilize a signal output by a first one of said plurality of first-typereceive chains to remove undesired signals from a signal output by asecond one of said plurality of first-type receive chains.
 2. The systemof claim 1, wherein said undesired signals comprise aliases of one ormore signals within one of said plurality of sub-bands processed by saidfirst one of said plurality of first-type receive chains.
 3. The systemof claim 1, wherein said undesired signals comprise harmonics of one ormore signals within one of said plurality of sub-bands processed by saidfirst one of said plurality of first-type receive chains.
 4. The systemof claim 1, wherein each of said plurality of first-type receive chainsis operable to downconvert, filter, and digitize said respective one ofsaid plurality of sub-bands of said received signal.
 5. The system ofclaim 1, wherein each of said plurality of first-type receive chainsdownconverts said respective one of said plurality of sub-bands of saidreceived signal utilizing a respective one of a plurality offixed-frequency local oscillator signals.
 6. The system of claim 5,wherein a frequency of each one of said plurality of fixed-frequencylocal oscillator signals is different than a frequency of each other oneof said plurality of fixed-frequency local oscillator signals.
 7. Thesystem of claim 1, wherein said one or more circuits are operable toenable and disable one or more of said plurality of first-type receivechains based on whether a channel to be output by said receiver islocated in one of said plurality of sub-bands of said received signalthat is processed by said one or more of said plurality of first-typereceive chains.
 8. The system of claim 1, wherein: said received signalencompasses a cable television band; and each of said plurality ofsub-bands of said received signal comprises a plurality of cabletelevision channels.
 9. The system of claim 1, wherein said one or morecircuits comprise at least one second-type receive chain that isoperable to concurrently process all of said plurality of sub-bands ofsaid received signal.
 10. The system of claim 1, wherein each one ofsaid plurality of sub-bands of said received signal is substantiallynon-overlapping with each other one of said plurality of sub-bands ofsaid received signal.
 11. A method comprising: receiving a first signal;processing each of a plurality of sub-bands of said received firstsignal via a respective one of a plurality of first-type receive chainsof a receiver; utilizing a signal output by a first one of saidplurality of first-type receive chains to remove undesired signals froma signal output by a second one of said plurality of first-type receivechains.
 12. The method of claim 11, wherein said undesired signalscomprise aliases of one or more signals within one of said plurality ofsub-bands processed by said first one of said plurality of first-typereceive chains.
 13. The method of claim 11, wherein said undesiredsignals comprise harmonics of one or more signals within one of saidplurality of sub-bands processed by said first one of said plurality offirst-type receive chains.
 14. The method of claim 11, comprisingdownconverting, filtering, and digitizing each of said plurality ofsub-bands of said received first signal via a corresponding one of saidplurality of first type receive chains.
 15. The method of claim 11,wherein each of said plurality of first-type receive chains downconvertsa respective one of said plurality of sub-bands of said received firstsignal utilizing a respective one of a plurality of fixed-frequencylocal oscillator signals.
 16. The method of claim 15, wherein afrequency of each one of said plurality of fixed-frequency localoscillator signals is different than a frequency of each other one ofsaid plurality of fixed-frequency local oscillator signals.
 17. Themethod of claim 11, comprising controlling whether one or more of saidplurality of first-type receive chains is enabled or disabled based onwhether a channel to be output by said receiver is located in a sub-bandof said received first signal that is processed by said one or more ofsaid plurality of first-type receive chains.
 18. The method of claim 11,wherein: said received first signal encompasses a cable television band;and each of said plurality of sub-bands of said received signalcomprises a plurality of cable television channels.
 19. The method ofclaim 11, comprising concurrently processing all of said plurality ofsub-bands of said received first signal via at least one second-typereceive chain of said receiver.
 20. The method of claim 11, wherein eachone of said plurality of sub-bands of said received first signal issubstantially non-overlapping with each other one of said plurality ofsub-bands of said received first signal.